| Composition of hydrogel(ratio of PVA to clay)||Amount of PVA added(g)||Amount of clay added(g)||Concencentration of DMSO/dye stock solution added(μM)||Amount of DMSO/dye added(mL)

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| Composition of hydrogel(ratio of PVA to clay)||Amount of PVA added(g)||Amount of clay added(g)||Volume H<sub>2</sub>O(mL)||Amount of mineral oil added(mL)

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|-

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| 90:10 PVA:110% NaMT||0.9099||0.1045||92||0.272

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| 90:10 PVA:110% NaMT||0.9099||0.1045||29||28

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|-

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| 50:50 PVA:110% NaMT||0.5076||0.4913||165||0.152

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| 50:50 PVA:110% NaMT||0.5076||0.4913||27||26

|-

|-

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| 90:10 PVA:110% Lamponite||0.9010||0.0998||92||0.272

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| 90:10 PVA:110% Lamponite||0.9010||0.0998||26||25

|}

|}

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Observations:

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*After the addition of dye/DMSO to the 110% Lamponite, the dye appeared to stick to very small spheres at the bottom of the beaker. Bright pink spheres immediately formed. This did not occur for the samples containing 110% NaMT.

Current revision

Objectives

Microsphere Preparation

Due to the relatively unsuccessful preparation of PVA/clay microspheres(the prepared spheres were either larger than a micrometer or did not appear at all), a new method was used for the preparation of PVA/clay microspheres.

General Protocol:

The desired ratio of PVA and clay was measured out. The total mass was ~1g.

The PVA/clay was placed in a 50mL beaker with a magnetic stir bar. 25mL distilled H2O were added to the beaker and the solution was heated to ~100°C and allowed to stir until complete dissolution of PVA/clay.

The magnetic stir bar was removed and 25mL of mineral oil was added to the beaker.

The contents of the beaker were poured into a blender to homogenize the solution and create an emulsion of the aqueous and organic layer in the attempt to create a suspension of microspheres.

The blender was turned on a low setting for 7 minutes.

The contents of the blender were poured into a beaker and the appropriate amount of DMSO/Rhodamine 6G solution was added.

The microsphere solution was placed in a freezer at -20°C for 24 hours and then removed and allowed to thaw for 24 hours.

Correction: The x-axis should be labeled Wavelength(nm). The image will be corrected

Observations:

Each of the samples had a very fast diffusion rate. If the spectra are viewed additively for each hydrogel sample, a significant amount of dye leaked out of the hydrogel sample in only 2 hours, in comparison to the hydrogels which remained in distilled H2O for one week and had minimal dye diffusion. This indicates that the dye must be added prior to the freeze-thaw crosslinking method.

Due to the fact that the dye did not immediately, completely diffuse out, the crosslinking of PVA/clay hydrogels slowed the diffusion rate of the dye.

Comparing the 50:50 ratio of PVA:clay and the 90:10 ratio, the hydrogels with 50:50 ratio had more dye leak out of the hydrogel than the 90:10 ratio. Perhaps indicates a more effective pressure stimuli.

In the future, when performing the diffusion tests, after taking a sample every fifteen minutes, the sample will be readded to the test beaker rather than discarded.